JPS6224256B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tool horn for an ultrasonic plastic welder.

When welding plastic using an ultrasonic plastic welding machine, the machining efficiency of the tool horn can be maximized by making the surface of the tool horn in contact with the plastic (processing surface) vibrate in the same phase longitudinally.

Figure 1a shows a tool horn consisting of the simplest columnar longitudinal vibrating body 10. An ultrasonic vibrator is coupled to the excitation surface 11 of one end face to give longitudinal vibration, and the other end face is made of plastic. This serves as a processing surface 12 on which pressure welding and welding processing is performed. The wavelength of the longitudinal vibration given to the longitudinal vibrating body 10 from the excitation surface 11 corresponds to the value obtained by dividing the sound velocity propagating through the material of the longitudinal vibrating body 10 by the frequency of the ultrasonic wave used, but the length of the longitudinal vibrating body 10 A length of 1/2 wavelength is generally used for l. The width w is
If it is less than 1/4 wavelength, the vibration displacement distribution on the machined surface 12 becomes uniform as shown in 1 in Fig. 1b, but as the width w exceeds 1/4 wavelength and approaches 1/2 wavelength, it becomes uniform. As a result, the vibration displacement distribution becomes different in magnitude between the center and both ends in the width direction, as shown in 2 in Figure 1b.
The closer it gets to 1/2 wavelength, the larger the difference becomes. When welding plastic, this makes it impossible to uniformly weld the welded portion, which is one of the constraints in manufacturing tool horns. Note that the thickness d of the vertical vibrating body 10 is set to be smaller than the width w.

To obtain a long welding surface, a tool horn as shown in FIG. 2a is currently used. This tool horn 14 has a rectangular plate shape, with one longitudinal end surface serving as an excitation surface 11 and the other end surface serving as a machining surface 12, with a plurality of slits 13 provided on the side surface between the machining surface 12 and the excitation surface 11. The vibration displacement on the machined surface 12 is made uniform. However, in reality, the distribution of vibration displacement on the machined surface 12 is often not uniform, as shown by 2 in Fig. 2b, but the vibration displacement difference is within a range that can uniformly weld the plastic. Currently, it is used in a shortened form.
The length and width of this slit 13, the spacing between the slits, etc. are changed based on experience and trial and error.
Not only is there a lot of wasted labor and economic loss, but you may even end up producing defective products that are completely unusable.

An object of the present invention is to eliminate the above-mentioned problems and to easily and reliably provide a tool horn having desired performance.

In order to achieve this objective, the present invention provides one end of a plurality of columnar longitudinal vibration resonators at the in-phase antinode point (loop point) of the vibration of a square bar that causes flexural resonance in an integer mode higher than the second order mode. The other end of the longitudinal vibration resonator is connected to the square bar at right angles, and the other end of the longitudinal vibration resonator is connected to the other end of the longitudinal vibration resonator. This is a tool horn for an ultrasonic welding machine with a processing surface of

As shown in Fig. 3a, the excitation surface 18 at one end is small and the transverse vibration is widened in the part near the excitation surface 18, and then the width is further increased near the machined surface 12 at the other end. Consider body 15. This longitudinal vibration resonator is one that can propagate only the longitudinal waves applied to the excitation surface 18 to the machined surface 12, and maintain a uniform vibration displacement and in-phase state on the machined surface 12. Therefore, considering this longitudinal vibration resonator 15 as one unit, a plurality of them are arranged horizontally in a row, and
If the excitation surfaces 18 of each longitudinal vibration resonator 15 are driven in the same phase and with the same driving force, the processed surfaces 12 of each longitudinal vibration resonator 15 will vibrate in the same phase and with the same vibration displacement. Third
Figure b shows an example in which three longitudinal vibration resonators 15 are connected horizontally, and as shown in Figure 3c, the vibration displacement of the machined surface 12 to which each longitudinal vibration resonator 15 is connected becomes flat. .

In this case, a driving device having a driving force for driving the excitation surfaces 18 of each longitudinal vibration resonator 15 in the same phase and with the same displacement is required. For ultrasonic plastic welding machines,
Since the current situation is to change the tool horn suitable for each type of machining, it is more convenient to use a welding machine to drive one point than to drive multiple points at the same time. be.

Therefore, the present invention utilizes the flexural vibration of a square rod to simultaneously drive a plurality of longitudinal vibration resonators in the same phase and with the same displacement.

Fig. 4a shows the square rod 16 having a length that allows it to deflect and resonate with the vibration shown by the vibration displacement curve 3 in the second mode, and Fig. 4b shows the square rod 17 with the vibration shown by the vibration displacement curve 4 in the third mode. The length is such that it resonates when deflected. 5 in the figure is the antinode (loop) point of vibration,
6 indicates a node point.

The excitation surfaces 18 of the longitudinal vibration resonator 15 shown in FIG.
FIG. 5 shows that the other ends of the longitudinal vibration resonators 15 are connected to make them continuous, and FIG. 6 shows that three longitudinal vibration resonators are connected to the square rod 17 in the same way.

In this way, the sides of the square rods 16 and 17 opposite to the longitudinal vibration resonator connection part are set as the excitation points 20, one excitation point 20 is excited on each of the square rods 16 and 17, and the square rods If deflection resonance is produced in 16 and 17, each longitudinal vibration resonator 15 can be longitudinally vibrated simultaneously with the same phase and the same displacement, and therefore the machined surface 12 can be vibrated with the same phase and the same displacement. In addition, an excitation point 20 that has an opposite phase relationship with the excitation point 20
The intermediate point 19 may be driven at one point. In actual use, the processing is performed while pressing the plastic with the processing surface 12, so in order to apply this static pressure so that the rods 16 and 17 do not bend, the driving is performed by applying vibration on one side in Fig. 5. point 20, and in FIG. 6 by the central excitation point 20.

5 and 6 are theoretical explanations of the tool horn according to the present invention. The longitudinal vibration resonator 15 of the tool horn shown in FIGS. Since the area changes discontinuously, the velocity and force of the longitudinal wave passing through it change rapidly at the stepped portions 7 and 8, and stress fracture occurs at the inner corners of the stepped portions 7 and 8. There is a risk that this may occur. FIG. 7 shows an embodiment that eliminates this problem. As shown in FIG. 7, by forming the stepped portions 7 and 8 into a concave curve and a horn shape,
Sudden changes in acoustic impedance when looking at the machined surface 12 from the excitation point 20 can be avoided.

When connecting the longitudinal vibration resonator 15 to the square rods 16 and 17, it is ideal to connect the excitation surface 18 of the longitudinal vibration resonator 15 with a line to the side surface of the vibration node 5 of the square rods 16 and 17. It is true. However, in practice, such a thing cannot be realized, so in order to reduce the influence of the rotational movement of the square bars 16 and 17 which are making flexural vibrations on the longitudinal vibration resonator 15, it is necessary to make them as thin as possible. As shown in Figure 8, the amplitude of the abdominal point is approximately 8.
It is necessary to keep the width to a certain level. If the width is larger than this, the vibration displacement will not be flat on the machined surface 12, and the vibration direction will also include an oblique component in addition to the component perpendicular to the machined surface. On the other hand, since the same phase and displacement are continuously required on the processing surface 12, a wide width is required. In this way, in order to make each longitudinal vibration resonator 15 continuous on the machined surface 12 side, the width in the direction of continuity is set to the machined surface 1.
It widens towards the second side.

As described above, the present invention utilizes the unprecedented idea of combining a square bar that causes flexural vibration and a longitudinal vibration resonator that causes longitudinal vibration, and can be used even with single-point drive to produce a long machining zone with the same phase and displacement. We can efficiently and freely design and provide tool horns that can form .

[Brief explanation of the drawing]

Figure 1a is a perspective view of a conventional tool horn with the simplest shape, Figure 1b is a diagram showing the vibration displacement distribution of the machining surface of the tool horn in Figure 1a, and Figure 2a is a conventional long-shaped tool horn. Fig. 2b is a diagram showing the vibration displacement distribution of the machined surface of the tool horn of Fig. 2a, and Fig. 3a is a perspective view of an example of a tool horn for obtaining a welded surface of the present invention. A perspective view of an example of a longitudinal vibration resonator,
Fig. 3b is a side view of three longitudinal vibration resonators shown in Fig. 3a connected horizontally in a row, and Fig. 3c is a side view of Fig. 3b.
Figures 4a and 4b are side views showing an example of the square bar constituting the tool horn of the present invention, and Figure 5 is a diagram showing the vibration displacement distribution of the machined surface of the longitudinal vibration resonator of the present invention. 6 is a side view of another embodiment of the tool horn of the present invention; FIG. 7 is a side view of still another embodiment of the tool horn of the present invention; FIG. 8 is a side view of another embodiment of the tool horn of the present invention;
The figure is a diagram for explaining the connection width between the longitudinal vibration resonator and the square rod of the tool horn of the present invention. 1, 2... Vibration displacement distribution, 3, 4... Vibration displacement curve, 5... Vibration antinode point, 6... Vibration node, 1
0...Longitudinal vibrating body, 11, 18...Excitation surface, 12...
... Machining surface, 13 ... Slit, 14 ... Tool horn, 15 ... Longitudinal vibration resonator, 16, 17 ... Square bar, 19, 20 ... Excitation point.

Claims (1)

[Claims] 1 One end of a plurality of columnar longitudinal vibration resonators is connected perpendicularly to the square rod at the in-phase antinode point of the vibration of the square rod that causes deflection resonance in an integer mode higher than the second order mode, and the longitudinal vibration resonators are A tool for an ultrasonic welding machine whose other ends are connected to each other, the side surface opposite to the longitudinal vibration resonator connection part of the square bar is the excitation point, and the other end surface where the longitudinal vibration resonator is connected is the processing surface. Horn.